It has now been found that polyurethane elastomers prepared from a hydrophobic difunctional telechelic linear non-crosslinked polyol without pendant chain branched groups of the above structure wherein the X's are hydroxyl-containing moieties such as --CH.sub.2 OH, --(CH.sub.2).sub.8 COO(CH.sub.2).sub.p OH and --COO(CH.sub.2).sub.p OH and permit the preparation of hydrophobic polyurethane elastomers with improved characteristics. Hydrolytic stability is improved. The effect of humidity aging on hardness, tensile strength, elongation, tear strength, hardness is significantly reduced. Low temperature flexibility of the resulting polyurethane elastomers prepared from the difunctional telechelic linear non-crosslinked polyol is significantly improved wherein glass transition temperature of the soft segment, Tg, is significantly lowered.
The difunctional telechelic linear non-crosslinked polyolefin without pendant chain branched groups wherein the X's are hydroxyl-containing moieties such as --CH.sub.2 OH, --(CH.sub.2).sub.8 COO(CH.sub.2).sub.p OH and --COO(CH.sub.2).sub.p OH is prepared by consecutive olefin metathesis reactions comprising an olefin metathesis reaction of an acyclic olefin with a linear terminal monofunctional group consisting of an ester moiety other than a vinyl group to prepare a linear terminal mono- or difunctional olefin wherein the functional groups are ester moieties of increased molecular chain length with other than terminal vinyl groups, and an olefin metathesis reaction of a linear terminal mono- or difunctional olefin with a cyclic olefin to prepare a linear terminal difunctional olefin of increased molecular chain length. The resulting linear terminal difunctional olefin wherein the functional groups are ester groups of increased molecular chain length has no pendant chain branched groups, and the molecular chain lengths are relatively uniform. The ester moiety is selected from the group consisting of an acrylate moiety, a methacrylate moiety, an allyl acetate, an undecylenate moiety, allyl propionate and allyl butyrate. Low molecular weight co-product olefins such as ethylene are removed from the olefin metathesis reactions by suitable means comprising evaporation, crystallization, purging the olefin metathesis reactions with an inert gas, and combinations thereof. The difunctional telechelic linear polyolefins wherein X is a hydroxyl moiety are prepared by conventional hydrolysis and alcoholysis reactions from the difunctional telechelic linear polyolefins wherein X is an ester moiety.
The resulting difunctional telechelic linear non-crosslinked polyolefin without pendant carbon groups, wherein the functional groups are ester moieties and have a 2.0 functionality number, are suitably substituted in conventional manner by reactive moieties selected from the group --CH.sub.2 OH, --(CH.sub.2).sub.8 COO(CH.sub.2).sub.p OH and --COO(CH.sub.2).sub.p OH, wherein p is 2 to 12.
The polydispersity of this novel class of difunctional telechelic noncrosslinked polyolefins is from 1.3 to 3.0. The polyolefins are soluble in common organic solvents and demonstrate no evidence of pendant carbon chains with multiple carbon attachments under high resolution nuclear magnetic resonance (NMR).
The difunctional telechelic linear non-crosslinked hydrophobic polyolefins accordingly have unique physical properties because of their linearity, non-crosslinked structure, low polydispersity and unsaturation and are capable of providing these properties of linearity, non-crosslinking, low polydispersity, and hydrophobicity to polyurethane elastomers of high molecular weight. The absence of vinyl groups as reactive terminal moieties permits the preparation of high molecular weight linear hydrophobic polyurethane elastomers without branching of the polymer chains, thus permitting the preparation of high density polyurethane elastomers with less permeability to gas and solvents and increased tensile strength versus polyurethane elastomers with branched chains.
It is therefore an object of this invention to provide a new group of polyurethane elastomers with improved properties prepared from difunctional hydrophobic telechelic linear non-crosslinked polyolefins.